This invention relates generally to gas turbine engine thrust reversers and more particularly to air seals for such reversers.
A gas turbine engine includes a turbomachinery core having a high pressure compressor, combustor, and high pressure turbine in serial flow relationship. The core is operable in a known manner to generate a primary flow of propulsive gas. A typical turbofan engine adds a low pressure turbine driven by the core exhaust gases which in turn drives a fan through a shaft to generate a bypass flow of propulsive gas. In the case of a high bypass engine this provides the majority of the total engine thrust.
Aircraft turbofan engines typically employ thrust reversers for ground deceleration. Known designs include “target” reversers, blocker-door reversers, and cascade or “doorless” reversers. Thrust reversers may be provided for the primary or bypass flows of an engine, or both. Each type of thrust reverser includes one or move components which are selectively moveable from a stowed position in which they do not affect engine thrust, to a deployed position in which some portion of the engine's thrust is turned or directed forward in order to slow the aircraft.
Thrust reverser components are relatively large and subject to air loads, vibration, thermal gradients, and other varying loads in operation. Accordingly, there is a limit to how small gaps and tolerances can be made, and some leakage of fan bypass flow occurs from the bypass duct to secondary flowpaths (i.e. inside the reverser). This results in a mixing pressure loss in the bypass duct that reduces net thrust, thus undesirably increasing specific fuel consumption (SFC).